Spark plug



Jan. 23, 1940. c;A s WEINERTH SPARK PLUG Filed Deo. 13, 1938 FEE- FIEL

I N VE NTOR. G60/PGE 5 ,5m/fem ATT( lRNEY.

Patented Jan. 23, 1940 UNITED STATESV PATENT" orties 2 Claims.`

This invention relates to a spark plug, and has particular reference to a spark plug of greater efficiency than the present day plug.

In plugs' of the present day where the tip of 5 the insulating member extends out beyond the metallic shell of the plug, there is a long distance for the heat to travel down this insulating member for dissipation in the metal part of said plug from whence it is dispersed into the engine block. rlhis causes excessive heating of the insulation tip which has a tendency to burn olf the positive electrode and shortens the life of the plug. Moreover, the excessive heating of the insulation tip often results in pre-firing of the combustible elements in the cylinder, as can be readily noted by the continuation of the engine to explode after the ignition is cut off.

In an effort to overcome these objections, the o end of the insulator has been placed within the shell of the plug itself which, of course, shortens the distance of travel for the heat from the electrodes, but this construction provides a dead gas pocket which will usually not be properly scavenged when the products of combustion are removed from the cylinder. Ofttimes the electrodes themselves are placed within this dead gas chamber, all of which will cause a sluggishness in the ignition of the compressed gases by virtue of the electrodes themselves being surrounded by waste gases.

The object of the present invention is to provide a spark plug in which the electrodes extend fairly within the compressed gas chamber.

Another ob-ject is to provide aspark plug in 35 which the distance of travel from the positive electrode to metal for heat dissipation is very short.

A further object of the invention is to provide a spark plug which has substantially no pocket between the insulator and shell.

The drawing illustrates embodiments of the invention and the views therein are as follows:

Figure 1 is a Vertical sectional view of a spark plug constructed according to my invention and of the crimped type, and

Figure 2 is a similar view showing the sealing nut type of spark plug.

As illustrated in the drawing, and particularly Figure 1, the shell 6 has an insulator 'I extending w' through the same. This insulator has a tip 8,

and a shouldered portion 9.

The shell E has an internal shoulder II at the electrode end I2 of said shell, and a sealing ring I3 is placed between this internal shoulder II D and the shouldered part 9 of the insulator.

The shell is provided with an attaching portion I 4; in the present instance shown as screw threads for engagement in a threaded hole in the cylinderv block when the plug is rotated with a wrench or other tool engaging the hexagonal 5 part i6. Beyond the shouldered part 9 of the insulator, the same flares, as at Il', to an enlarged diameter I8 which terminates in a reducing shoulder I9. A sealing ring EI ts against this shoulder I9 and the metal of the shell is 10 crimped over, as at 22, to seal the rings i3 and 2l rmly between the metal and insulator in order to insure against the escape of gases therethrough. The insulator may then taper outwardly, as at 23, to a ribbed end 24. The outer end of the insulator is provided with a centrally located hole ES from which extends entirely through the insulator a smaller hole 2l. A conductor 28 passes through this hole 2l while the screw threaded part 29 thereof is cemented into 20 the hole 26, as shown at 3| and 32. The inner end of the conductor 2B acts as a positive electrode 33 while a ground electrode 3ft is connected with the metal shell S. The distance which the electrode 33 extends through the insulation tip 25 8 is determined by the plate 36 at the other end of the conductor 28, while a screw threaded part 3l is provided as a terminal for said plug. The tip 8 is of such diameter that there is only a sliding lt between it and the bore 38 at the elec- 30 trode end of the shell so that there is no pocket provided in this type of plug. The sealing ring I3 is in close proximity to the electrode end of the shell so that there is a very short distance for the heat to travel from the electrode to metal where the heat is dissipated. This will prevent the burning and pitting of the electrode caused by excessive heat, and the insulation tip 8 will not heat or get red hot, as is the case in many types of spark plugs now on the market. 40

In Figure 2 the insulating member has a shoulder 4I against which the sealing ring 2 rests, while the casing 43 is internally threaded, as at 44, to receive the threads 4t of a sealing nut 4l. The electrode end of the plug shown in 45 Figure 2 is precisely the same as that of the plug shown in Figure 1, the sealing ring I 3 being in close proximity to the electrode end I2 of the shell.

In spark plugs heretofore manufactured and used, the inner sealing ring corresponding to the sealing ring I3 has usually been located at or near the point X in Figure l, and Z in Figure 2, and the parts have been arranged so that the insulation tip was in most cases excessively heated and the positive electrodes after a short time of use become pitted kand burnt oi so that the eicient life of the ordinary spark plug is short compared to the life of a plug manufactured according to this invention.

Spark plugs constructed as illustrated and described herein have been tested over long periods of use, and it has been found that there was no burning away of the electrodes or insulation tip,V and that Ythe electrodes were not pitted or injured in any way.

Of course, the spark plug illustrated and described herein may be modified and changed in various Ways without departing from the invention herein set forth and hereafter claimed.`

The invention is hereby claimed as follows:

1. A spark plug having a metallic shell, a single piece insulator having a central hole through same, a positive electrode adapted to be passed through the hole in said insulator in order that its substantially pointed ring end may extend outward from said insulator, said shell having an internal shoulder, a reduced end on said insulator passing through and in close proximity to said shoulder, the inner face of said shoulder having a depth not greater than the thickness of any longitudinal part of said shell, and a substantially pointed ground electrode connecting said shell and extending from one side of and beyond the end of said insulator.

2. A spark plug having a metallic shell, a single piece insulator having a central hole through same, a positive electrode adapted to be passed through the hole in said insulator in order that GEORGE S. WEINERTH. 

